AMD 7950 performance degradation 3,1 -> 5,1

Discussion in 'Mac Pro' started by fuchsdh, Sep 24, 2014.

  1. fuchsdh macrumors 6502a

    Joined:
    Jun 19, 2014
    #1
    So I just swapped the Radeon 7950 I had sitting in my 3,1 to the new 5,1 I got. Running Valley benchmarks, however, I'm seeing a dramatic drop in performance. On my 3,1 I got scores of ~1230/29.5 average FPS. And now I'm getting 830/19.8 on the same Extreme HD preset, which is basically what I got with my 5770 in the 3,1. No temps seem to be out of whack, so I'm wondering what the possible issue could be.
     
  2. gochi macrumors 6502

    Joined:
    Mar 31, 2011
    #2
    have u updated drivers of 7950?

    that drop in performance makes no sense whatsoever.
     
  3. fuchsdh thread starter macrumors 6502a

    Joined:
    Jun 19, 2014
    #3
    I was running the same OS on both. I assumed OS X had the drivers necessary.
     
  4. msbc macrumors newbie

    msbc

    Joined:
    Jul 27, 2011
    Location:
    Melbourne, Australia
    #4
    I have the 7950 in a MP5,1, 10.9.4. I'd be happy to provide a comparison benchmark if you detail the one your running.

    Mark
     
  5. fuchsdh thread starter macrumors 6502a

    Joined:
    Jun 19, 2014
    #5
    Extreme HD preset (no changes made to the option.)

    Ran it again.

    [​IMG]

    Just checked Sapphire's site, they say no reason to use the driver if you're 10.8.3+

    The only "off" part of my config at present is that I'm running just 4GB of RAM while I await a 24GB 1333 kit. But I wasn't aware the Valley benchmarks were influenced by RAM, heavily or at all.
     
  6. h9826790 macrumors 604

    h9826790

    Joined:
    Apr 3, 2014
    Location:
    Hong Kong
    #7
    Did you try reseat the card, or SMC reset etc?

    Is there anything strange thing the system profile?

    How about other benchmark software? All running low?
     
  7. netkas macrumors 65816

    Joined:
    Oct 2, 2007
    #8
    try

    sudo rm -rf /System/Library/Extensions/AppleIntelCPUPowerManagement.kext
    sudo touch /System/Library/Extensions


    helps to prevent 7950 being slow in 10.9+ on MP3,1. Might help you as well.

    There is no known regressions caused by this hack.
     
  8. fuchsdh thread starter macrumors 6502a

    Joined:
    Jun 19, 2014
    #9
    Did an SMC reset, reseated the card, double-checked the 6pin connectors, and ran the terminal command + did a restart. It got better... not any better than my 3,1, though.

    [​IMG]

    The fans are also spinning up audibly on the 5,1 where they never did on the 3,1--getting to 1900RPM on the PCIe slots and 1400 on the PSU. Do I just need to smcFan to stop it from doing that?
     
  9. mikeboss macrumors 65816

    mikeboss

    Joined:
    Aug 13, 2009
    Location:
    switzerland
    #10
    same here. unfortunately this is perfectly normal behavior. my 3,1 was much more quiet than 4,1/5,1 when the GPU is used heavily.
     
  10. h9826790 macrumors 604

    h9826790

    Joined:
    Apr 3, 2014
    Location:
    Hong Kong
    #11
    If the fan speed stay there (not under heavy load), you can use SMCFanControl to set the PCIe fan to max, and then turn it back to auto straight away. The fan should slowly spin down and back to it's normal speed (it takes few minutes to spin down). The idle speed should be 800RPM even though with the HD7950 installed.
     
  11. fuchsdh thread starter macrumors 6502a

    Joined:
    Jun 19, 2014
    #12
    Well drat. I noticed that it was a bit louder in general, as well. Let it not be said then that the 3,1 has its merits! :)

    I'll try that when I get home. Thanks.
     
  12. flowrider macrumors 601

    flowrider

    Joined:
    Nov 23, 2012
  13. h9826790 macrumors 604

    h9826790

    Joined:
    Apr 3, 2014
    Location:
    Hong Kong
    #14
  14. mikeboss macrumors 65816

    mikeboss

    Joined:
    Aug 13, 2009
    Location:
    switzerland
    #15
    yes, it can :p

    edit: ah, sorry. do you mean the fan on the graphics card? this it can't though.
     
  15. fuchsdh thread starter macrumors 6502a

    Joined:
    Jun 19, 2014
    #16
    Well I don’t think the issue is the actual Radeon’s fan, it’s the PCI fan on the MP. So if both let me throttle that, I will try it :)
     

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